🚀 go-pugleaf

In article <gfATnhq00iUzI1mV0H@andrew.cmu.edu>, cd1i+@andrew.cmu.edu (Christopher Bradley Devlin) writes:
> 
> What is all this talkk of particles blowing through the housing?  What
> particles?  The original premise was that these flywheels disintegrate

particles of the destroyed rotor

> into a light cotton like fiber.  Heat, yeah, but how much kinetic energy
> does a flying piece of cotton have?

The same as it did when it was part of the rotor - one hell of a lot.
Plenty to blow through any of the simplistic housing proposed in this
discussion.  Remember, kinetic energy is 0.5 M V^2.  The M may not be a
lot, but the V is beyond anything in your experience (these discussions
of speeding trucks and bullets are just nonsense in comparison).  And it's
the V that's squared there.  The impact of the fiber with the housing
is well beyond any elastic limits - it generates a shock wave in the housing,
and melts or even vaporizes the housing at the point of impact.

> And there are ways of dealing with too much heat.  How about ceramic
> thick films on the inside of the housing as thermal sheilds?  Or a
> ceramic housing?

Ceramic.  Big deal.  A meteor melts the rocks it impacts and it is not
moving as fast as the flywheel rotor - and ceramic is nothing more than
glassy rock.   It will melt.

> I think I'll look these up, does anyone have a reference?

Look what up?  The melting temperatures for ceramics?  Lots of references,
but you don't understand the physics here.  The particles have so much
energy that they will melt any solid in existance.  This has more to
do with the molecular behavior of the material - the impact velocity is
so high that the atoms are forced well beyond any sound speeds.  They
then form a shockwave, completely disordeing the material, leaving it
in a fluid state and creating a great deal of heat.  Just check some
sound velocities and compare that to the velocity of the particles from the
rotor.  That starts to give you an idea of what kind of regime we're in.


--
Richard Stead
Center for Seismic Studies
Arlington, VA
stead@seismo.css.gov